1. Field of the Invention
The present invention relates to an adjustable head for a wrench. In particular, the present invention relates to a wrench including a handle and a head that can be pivotally adjusted to and retained in a desired position relative to the handle.
2. Description of the Related Art
FIGS. 1 through 3 of the drawings illustrate a conventional wrench that includes a handle 1 and a head 10 that can be pivotally adjusted to a desired position relative to the handle 1, as disclosed in, e.g., Taiwan Utility Model Publication No. 380468. The handle 1 includes a pair of lugs 2 on an end thereof, and a pin 3 is extended through aligned holes 4 in the lugs 2 and a pin hole 13 in a pivotal portion 11 of the head 10, thereby pivotally connecting the pivotal portion 11 of the head 10 to the lugs 2 of the handle 1. A plurality of teeth 12 is formed along an arcuate outer surface section of the pivotal portion 11 for releasably engaging with a pawl or catch 15 mounted in the end of the head 10. Thus, the head 10 moves together with the handle 1 for driving fasteners when the catch 15 is engaged with the teeth 12 of the head 10. And the head 10 can be pivoted to a desired position relative to the handle 10 when the catch 15 is disengaged from the teeth 12 of the head 10. In this wrench, formation of the teeth 12 formed along an entire arcuate outer surface section of the pivotal portion 11 causes a reduction in the thickness of the pivotal portion 11; namely, the distance from a periphery delimiting the pin hole 13 to the dedendum circle of the pivotal portion is “L”. As illustrated in FIG. 1, the pivotal portion 11 is subjected to a torque at sections 13a and 13b when the wrench is turned along, e.g., clockwise for driving a fastener. It was found that cracks 14 are apt to be generated in the torque-bearing section 13b. The torque-bearing section 13b is damaged when the torque applied to the wrench is relatively large. The device for retaining the head in a desired position relative to the handle sacrifices the torque-bearing capacity of the wrench.
FIGS. 4 through 6 illustrate another conventional wrench that includes a handle 5 and a head 20 that can be pivotally adjusted to a desired position relative to the handle 5, as disclosed in, e.g., Taiwan Utility Model Publication No. 421111. The handle 5 includes a pair of lugs 6 on an end thereof, and a pin 7 is extended through aligned holes 8 in the lugs 2 and a pin hole 24 in a pivotal portion 21 of the head 20, thereby pivotally connecting the pivotal portion 21 of the head 20 to the lugs 6 of the handle 5. A plurality of teeth 22 is formed along an arcuate outer surface section of a left part (FIG. 5) of cylindrical section of the pivotal portion 21 for releasably engaging with a pawl or catch 26 mounted in the end of the head 20. Thus, the head 20 moves together with the handle 5 for driving fasteners when the catch 26 is engaged with the teeth 22 of the head 20. And the head 20 can be pivoted to a desired position relative to the handle 20 when the catch 26 is disengaged from the teeth 22 of the head 20 by means of sliding the catch 26 to a right part of the cylindrical section of the pivotal portion 21. An arcuate outer surface section 23 of the right part of the pivotal portion 21 must have a profile slightly lower than the dedendum circle of the teeth 22 to allow sliding movement of the catch 26 along a direction transverse to a longitudinal direction of the handle 5. Namely, the catch 26 cannot be slid to the right part of the pivotal portion 21 if the right part of the pivotal portion 21 has a profile higher than the dedendum circle of the teeth 22. Hence, the thickness of the right portion of the pivotal portion 21 is reduced, and the distance from a periphery delimiting the pin hole 24 to the arcuate outer surface section 23 of the pivotal portion is “L1”, which is smaller than “L” in the above wrench. As illustrated in FIG. 4, the pivotal portion 21 is subjected to a torque at sections 24a and 24b when the wrench is turned along, e.g., clockwise for driving a fastener. Similar to the above wrench, cracks 24 are apt to be generated in the torque-bearing section 24b, and the torque-bearing section 24b is damaged when the torque applied to the wrench is relatively large. In the wrench shown in FIGS. 4 through 6, the device for retaining the head in a desired position relative to the handle also sacrifices the torque-bearing capacity of the wrench.